<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>map</title>
    <script type="text/javascript">

        let arr = ['1', '20', '-5', '3'];

        console.log(arr)

        arr = arr.map(s => parseInt(s));

        console.log(arr);

        arr = arr.map(s => 10 + s);

        console.log(arr);


        arr = arr.map(s => Math.abs(s) - 2 * Math.abs(s));

        console.log(arr)
    </script>
</head>
<body>

</body>
</html>